Replace atom in `Atoms` object
Hi, I think it would be nice to allow replacing one atom in the Atoms
object so that something like this would work:
from ase import Atom
from ase.build import molecule
atoms = molecule('H2O')
atoms[0] = Atom('O')
In the current state of the things the error I get is:
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
<ipython-input-8-984b4fdbeffd> in <module>
----> 1 atoms[0] = Atom('O')
AttributeError: __setitem__
Seem to be quite a trivial fix, probably there was a reason why this has not been implemented.